1. Field of the Invention
The present invention relates to a toner dispersing mechanism, and a developing device and an image forming apparatus provided therewith, the toner dispersing mechanism being mounted to an electrophotographic image forming apparatus such as a copier, a printer, and a facsimile, and dispersing toner replenished from a toner storage container such as a hopper and a container into a developing device.
2. Description of Related Art
Conventionally, for facilitation of the maintenance, a predetermined amount of toner is filled in advance into the developing device mounted to the image forming apparatus, and the developing device itself is replaced when the toner is depleted. However, the developing device cannot be frequently replaced from an economic viewpoint, and a toner capacity of the developing device is inevitably increased for performing image formation on many sheets to some extent. Thus, the above-mentioned developing device is difficult to downsize. Under the circumstance, in order to achieve downsizing of the developing device, there has been proposed a developing device of a type to which toner is supplied from outside.
In the developing device of the toner supply type, a lump of toner is sometimes replenished into the developing device when toner fluidity is reduced owing to use environments and the like. Thus, there is a risk that the mixing property of the lump of toner and developer existing in the developing device are deteriorated and a developer thin layer formed on a developing roller is disturbed, with the result that image failures such as an image density unevenness and fogging occur.
Under the circumstance, there have been proposed various technologies for suppressing occurrence of the image failures by preceding dispersion of the toner replenished into the developing device. For example, as disclosed in the first related art, there has been known a developing device in which a matrix member (mesh) and a brush-like developer supply roller are arranged between a developer carrier and a developer storage portion. Further, as disclosed in the second related art, there has been known a developing device provided with a toner-replenishing-port stirring member for stirring toner in a toner replenishing port of a toner hopper. Still further, as disclosed in the third related art, there has been known a method in which a toner dispersing member constituted by a core and a cylindrical foam member is arranged so as to close a replenishing port of a toner bottle, and toner is dropped little by little into a developing device by rotation of the toner dispersing member.
Meanwhile, as disclosed in the fourth related art, there has been known an image forming apparatus which includes an auxiliary stirring container for separately receiving toner replenished from a toner replenishing container and carrier replenished from a carrier replenishing container and sufficiently mix and stir the toner and the carrier with use of a stirring/conveying member having a screw-like shape, and in which developer preliminarily mixed in the auxiliary stirring container and having a stable charging property is supplied to the developing device.